public class vrv {
    class Solution {
        public int mySqrt(int x) {
            if(x<1){
                return 0;
            }
            long left = 1,right = x;
            while(left<right){
                long mid = left + (right-left+1)/2;
                if(mid * mid <= x){
                    left = mid;
                }
                else{
                    right = mid-1;
                }
            }
            return (int)left;
        }
    }
}
